Low temperature cracking of asphalt pavements is a major distress in cold climates. Asphalt mixture strength is a fundamental parameter when designing pavements with increased durability. At low temperatures, asphalt mixtures have quasibrittle behavior with nominal strength strongly dependent on the structure size. In this paper, a simple method to relate the probability distribution function of strength of quasibrittle materials to the mean strength size effect is proposed. This is based on the finite weakest link model, which relates the cumulative distribution function of structural strength to the size dependence of the mean strength curve. A comprehensive experimental set of tests, which includes both mean size effect tests and strength histograms on specimens of asphalt mixture at low temperature, is used to verify the proposed method. The predicted mean strength curve obtained with this method is found to be in very good agreement with the experimental measurements on asphalt mixture specimens of different sizes, providing evidence of the validity of the proposed formulation. In the meanwhile, the effect of the size of the asphalt mixture Representative Volume Element (RVE) on the strength size effect prediction is also evaluated.